= Standard Model
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{title2=SM}
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The Standard Model is the <quantum field theory> of quarks, leptons and their strong, weak and electromagnetic interactions, organized by the <gauge group> $SU(3)_c\times SU(2)_L\times U(1)_Y$. <Quantum chromodynamics> describes the color sector; the <electroweak interaction> combines the remaining gauge fields with the <Higgs field>.
<Electroweak symmetry breaking> leaves the electromagnetic $U(1)_Q$ unbroken. The <W bosons> and <Z boson> become massive, while the <photon> stays massless; <Yukawa interactions> generate charged-fermion masses. This structure relates scattering, decay and particle-production processes using a common set of couplings. Predictions require specifying parameters and the approximation used, not only listing the group.
The minimal renormalizable field content has massless neutrinos. Observed <neutrino oscillations> require masses and mixing, motivating extensions such as the <Weinberg operator> or additional neutrino fields. The Standard Model also does not supply a quantum description of gravity.
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